Green and innovative extraction of polyphenols from Rhamnus alaternus using natural deep eutectic solvents and evaluation of their bioactivities

What if the key to unlocking nature's antioxidant treasure chest lies not in harsh chemicals, but in a simple, eco-friendly mixture? A new study shows that natural deep eutectic solvents can efficiently extract polyphenols from a Mediterranean shrub, revealing potent bioactivities.

Plants are walking pharmacies, packed with phenolic compounds that act as powerful antioxidants. But getting these valuable molecules out of plant tissue has often required harsh, polluting solvents. Now, researchers are turning to a greener alternative: natural deep eutectic solvents (NaDESs), made from cheap, biodegradable components like choline chloride and glycerol.

In this study, the team used choline chloride-based NaDESs to extract total phenolic compounds (TPC) from the leaves, pods, and roots of Rhamnus alaternus, a shrub known for its medicinal properties. They then measured the antioxidant and antibacterial activities of each extract. The results were striking: extracts obtained with a choline chloride-glycerol mixture boasted high TPC values (between 437.7 and 317.0 mg GAE/100 g d.w.) and showed the best antioxidant performance across multiple assays, including ABTS, DPPH, reducing power, and iron chelation.

In contrast, extracts made with choline chloride-urea showed low antioxidant capacity, highlighting the importance of solvent choice. The most promising extracts were further analyzed using HPLC-MS/MS to identify their bioactive compounds. This work suggests that NaDES-based extraction is not only efficient and selective but also sustainable, offering a green path to harnessing plant power for nutraceutical and antimicrobial applications.

Key Points

• Choline chloride-glycerol NaDES extracts had high phenolic content.
• These extracts showed strong antioxidant activity in multiple assays.
• NaDES method is selective, efficient, and sustainable for polyphenols.